Case-hardening material and process of making same.



MICHAEL KIRCI-IHOFF, JR., OF CHICAGO, ILLINOIS.

CASE-HARDENING MATERIAL AND PROCESS OF MAKING SAME.

No Drawing.

T 0 all whom it may concern Be it known that I, MICHAEL KmoHHoFr, Jr., a citizen of the United States, and res1- dent of Chicago, Cook county, Illinois, have invented a new and useful Case-Hardening Material and Process of Making Same, of which the following is a. specification.

My improvement in case-hardening material consists principally of leather prepared in a peculiar manner, a small proportionate quantity of calcium hydroxid and a sodium salt, these materials being so completely and thoroughly compounded and intermingled in the process of manufacture that each portion of the leather carries its proper proportionate part of the chemicals.

I am aware that leather both untreated and carbonized has heretofore been used in the process of cementation or case-hardening, and I do not, therefore, claim the exclusive use of leather for compounding such materials or for use in case-hardening.

I prepare my material by first taking a quantity of leather, preferably scrap bark tanned leather, and boiling this leather or steaming it until it has been brought to a sticky or gluey condition or partially so, that is the leather is heated in the presence of moisture until the strength of the leather is greatly reduced so that when the leather is dried and the moisture is driven 0E the leather is amorphous or substantially with out grain and is brittle and can be easily broken up. I grind or pulverize the amorphous leather into small granules or particles of suitable size, the larger ones preferably not over inch in diameter. As the leather is brittle'a large proportion of the material will be reduced to relatively small size or powder, and one valuable feature of my invention resides in the fact that I consume all of this material, even the finest powder. I thus reduce the treated leather scraps to comminuted condition in order to reduce the mass to a minimum volume and in order to be able to bringeach particle thereof into close contact with other chemicals which I use. Having reduced the leather to this granulated condition I pack it relatively solid into aretort which is liquid sealed, and I heat it'in the retort to about 1400 to 1600 degrees Fahrenheit, thus charring or coking the leather and causing the ground material to adhere and solidify into a substantially solid mass. That is the mass is not spongy or full of holesbut-is,

Specification of Letters Patent.

Patented Oct. 10, 1916,

Application filed October 9, 1915. Serial N 0. 54,964.

when taken from the retort, solid and hard. I may use this charred or coked leather in the case-hardening of steel, without further treatment, except to break it up into particles of suitable size, but, in order to provide a material which will more efliciently effect the case hardening of the steel or iron I preferably combine the boiled and dried or amorphous leather, in the comminuted or granulated form, with certain chemicals.

I preferably use calcium hydroxid and some sodium salt, such as sodium chlorid or common salt, and I mix these materials in the proportions of one hundred parts b weight of the ground amorphous leather to five parts of calcium hydroxid and live parts of the sodium salt. The leather, being in small granules or particles, can be thoroughly intermingled and mixed with the chemicals and I effect this thorough distribution of the chemicals and the leather by stirring the mixed material in a suitable vessel whereby each particle of the leather is placed in contact with a proportionate quantity of the chemicals. mixed the leather particles with the chemicals I retort the mass in a liquid sealed retort as described above for the leather alone. This heating of the mass in a retort drives off the various gases from the leather content and reduces the weight of the product to about forty or fifty pounds, thus increasing the proportionate quantity of each of the chemicals to about 5% of the resultant material. Among other advantages which the addition of the chemicals produces is to reduce the oxidation of the leather to a minimum in the subsequent case-hardening process for which the material is produced. I thus heat the mixture in the liquid sealed retort until the leather is charred or coked and in this process the leather first becomes soft and sticky and the chemicals with which it is mixed adhere to the leather the whole becoming a conglomerate mass and the chemicals partly absorbed and partly enveloped by the leather. The heating being continued the leather is carbonized and hardened and the chemicals and leather solidify into a substantially solid mass which is noncrystalline and amorphous and made up of leatherparticles intermingled, mixed, covered and impregnated with the chemicals and all stuck solidly together. The mass is brittle and easily reduced by "grindingto various sized particles for use in the casehardening or cementation process after the manner usually employed in the use of such materials.

I find that although the temperatures I use in retorting the mixture preferably from 1100 to 1600 Fahrenheit are not high enough to completely fuse the chemicals,

particularly the calcium hydroxid, nevertheless they are absorbed into and permanently secured to the leather in such a way that each particle of the leather thereafter carries its due proportion of the chemicals, the leather being in fact impregnated with the chemicals.

While I have described my material as comprising two chemicals I can make use of p but one thereof with excellent results and I make my material by the use of the calcium hydroxid alone or with the sodium salt, preferably common salt.

. material consists of the charred treated g to leather thoroughly intermingled and mixed Patent z- 1 1. The method of preparing a casehardening or cementing material which consists in heating a quantity of leather in the presence of moisture, until the leather becomes sticky or gluey, drying the mass until it is brittle, reducing the mass by grinding to suitably sized particles and thereafter subjecting the material to a relatively high temperature in a compacted condition in a liquid sealedretort thereby charring and solidifying the material 2. The method of preparing a casehardening or cementing material which consists in boiling a quantity of leather in water until the leather becomes sticky or gluey, drying the mass until it is brittle, reducing the material to suitably sized particles, and thereafter subjecting the material in a compacted condition to a relatively high temperature in a liquid sealed retort until the. material is solidified and charred.

3. The method of preparing a casehardening material which consists in heating a quantity of leather in the presence of moisture until the leather becomes sticky or gluey, then drying the mass until it becomes brittle, grinding the mass to reduce This resultant it to particles of suitable size, thoroughly mixing the material with a small percentage of calcium hydroxid and a sodium salt and subjecting the mass in a compacted condition to a relatively high temperature in a liquid sealed retort until the leather content thereof is charred.

4:- The method of preparing a casehardening material which consists in heating a quantity of leather in water until the leather becomes sticky or gluey, drying the mass until it becomes brittle, reducing the material to particles of suitable size, mixing the material with a small percentage of calcium hydroxid and a sodium salt, and subjecting the mass to a relatively high temperature in a liquid sealed retort until the leather content thereof is charred.

5. The herein describedprocess of making a case-hardening material which consists in heating a relatively large quantity of leather in the presence of moisture until it loses its strength and becomes sticky or gluey, drying the mass until it becomes brittle, reducing the mass to particles of suitable size, mixing the prepared leather with calcium hydroxid and a sodium salt in the proportion of one hundred parts by weight of prepared leather, five parts of calcium hydroxid and five parts of the sodium salt and subjecting the mixed material in a compacted condition to a temperature of 1400 to 1600 degrees Fahrenheit in a liquid sealed retort until the leather content thereof is charred.

6. The herein described process of making a case-hardening material which consists in boiling leather in Water until it becomes par tially gluey in character, drying the mass until it becomes brittle, reducing the mass to particles of suitable size by grinding, mixing the prepared leather With calcium hydroxid and a sodium salt in the proportion of one hundred parts by Weight of prepared leather five parts of calcium hydroxid and five parts of the sodium salt and sub- :jecting the mixed material in a compacted condition to atemperature of 1400 to 1600 degrees Fahrenheit in a liquid sealed retort until the leather content thereof is charred.

7. The herein described case-hardening material which comprises charred leather, a small percentage of calcium hydroxid and a small percentage of a sodium salt.

8. The herein described case-hardening material comprising charred leather impregnated with a small percentage of calcium hydroxid and sodium salts.

In testimony whereof, I have hereunto set my hand this 4th dayof October, 1915, in the presence of one subscribing witness.

MICHAEL KIRCHHOFF, JR.

WVitness:

EDWARD FAY WILSON.

.Gopie! of this patentmay be obtained totfifvecents each, by-addressing the con missioner or Ifatentl, 's -"WKWmD-Q" a 1 

